1. Field of the Invention
This invention relates to motor control units, and, in particular, to an input/output adapter configured to be mounted directly to the motor control unit to allow discrete wiring of control units having mass-termination connectors.
2. Disclosure of Related Art
It is common in industry today to utilize a programmable motor control unit to generate excitation signals to control the operation of a motor. The control unit typically includes one or more control circuits disposed within a housing and electrically connected to the motor. The control unit also includes an external interface to the control circuits disposed on the front of the control unit. The interface allows the user to program the control circuits by sending input signals to, and receiving output signals from, the control circuits.
The conventional interface for a motor control unit typically includes various connectors, including mass-termination connectors and/or terminal strips, that allow a computer or other programming means to be connected to the control circuits and to transmit signals to and receive signals from the control circuits. Mass-termination connectors provide a single connection for transmitting a plurality of signals. Therefore, such connectors promote ease of assembly between the control unit and programming means. Terminal strips provide individual connections for individual signals. Although terminal strips make the assembly of the control unit and programming means more difficult, the terminal strips allow easier adjustment and control of individual signals. Interfaces for conventional motor control units typically incorporate either mass-termination connectors or terminal strips for transmitting/receiving a given set of input/output signals, but do not incorporate both types of connectors for the same signals. As a result, the user of the motor control unit is restricted to using one type of connector between the control unit and the programming means even though a different type of connector may be more suitable for a particular application. Attempts have been made to provide the benefits of both mass-termination connectors and terminal strips by providing adapters for control units having mass-termination connectors. The adapters typically include terminal strips that can be electrically connected to the mass-termination connectors of the control unit through a cable. Such adapters are typically mounted to the side of the control unit (i.e., not the interface). These conventional adapters are costly in terms of materials, assembly time, and space requirements. Moreover, the interconnecting cables of these adapters generate a significant level of electromagnetic interference.
There is thus a need for an adapter and a motor control unit that will minimize or eliminate one or more of the above-mentioned deficiencies.